Continuous casting apparatus for casting hollow billets



July 18, 1967 G. c. EARL, JR

CONTINUOUS CASTING APPARATUS FOR CASTING HOLLOW BILLETS Filed Sept. 10,1964 l H a 457f @w ATTORNEYS L D INVENTOR M George C. Earl, Jr.

BYwg

United States Patent 3,331,430 CONTINUOUS CASTING APPARATUS FGR CASTINGHOLLOW BILLETS George C. Earl, Jr., Severna Park, Md'., assignor t0Kennecott Copper Corporation, New York, NY., a corporation of New YorkFiled Sept. 10, 1964, Ser. No. 395,541 8 Claims. (Cl. 164-281) Thisinvention relates to apparatus for the continuous casting of metal suchas copper, brass or aluminum, and has for its object the provision of animproved apparatus for supporting and protecting graphite mandrels usedin graphite molds to cast hollow billets.

Apparatus for continuously casting hollow billets usually comprises amold having an inner lining of graphite, a graphite mandrel suspended inthe mold forming an annular upright space in which the metal is pouredand solidified, means for lubricating the graphite surfaces and meansfor cooling and vibrating the mold and drawing the cooled billet out ofthe mold. The improved apparatus of the invention is used in a castingapparatus of this type.

The improved apparatus of the invention comprises means for supportingand holding a graphite mandrel in position inside a graphite mold. Thegraphite mold is secured inside a metal support and the improvedapparatus for supporting the mandrel is removably attached to the moldsupport, and is constructed to secure and center the mandrel in themold. The invention is advantageously applicable to mandrels having ahead portion with a mounting flange and a hollow head open at the topinto which a siphon tube is inserted for flowing metal into the mold. Apreferred type of mandrel has a receptacle or cup in the head forreceiving the molten metal and ducts through which the metal flows intothe casting of the mold.

The apparatus includes a plate cover having an opening which permits thesiphon to enter the hollow head. It is necessary that the mandrel headextend above the level of liquid maintained in the mold in order toconfine the metal in the head so that it can flow into the mold. Also,the extended head serves to define the space between the mold and themandrel so that a hollow billet can start forming where the metal ismolten. This leaves a part of the mandrel head exposed to the atmosphereand since the mandrel is in contact with hot metal, for example at about1000 C. for copper, the exposed mandrel portion is subject to oxidationand resulting deterioration. The mounting support of this invention hasa depending tapered skirt which covers a major part of the otherwiseexposed mandrel head and protects it from oxidation. The skirtpreferably tapers to a thin edge to enlarge the space near the surfaceof the metal in the mold to permit the use of floating carbon orgraphite beads to minimize oxidation of the mandrel head as will bedescribed hereinafter. Additionally the tapered support permits theoperator to view the level of metal in the mold and regulate the flow ofmetal accordingly.

The mandrel support member and associated means for securing the mandrelin the metal mold support are constructed to provide a small space forthe operator to see the level of metal in the mold from nearly theentire circumference of the casting.

In the accompanying drawings FIG. 1 is a plan View of the top of acontinuous casting mold showing the mandrel mounting support,

FIG. 2 is a side elevation, with parts in section, taken at 22 of FIG.1, and

FIG. 3 is a side elevation, with parts in section, taken at 33 of FIG.1.

The apparatus of FIG. 1 comprises a metal mold sup- 353L439 PatentedJuly 18, 1967 port 1, circular in cross-section, a graphite mold orliner 2, a graphite mandrel M, coupling ring 3, preferably formed in twoparts and bolted in snug contact with the mold support 1. The support 1and the mold 2 are preferably provided with cooling means and the mold 2with lubricating means (not shown). The mandrel support 4 has a centralcircular part in which the recess 5 is formed and three radially spacedlegs 6 which rest on the mold support 1 and have depending flanges 7through which bolts 8 connect the legs 6 to the ring 3. The flanges 7center the mandrel support on the mold support 1. The annular recess 5receives the annular flange 9 of the mandrel head 10 which is preferablycircular in transverse or horizontal section. The mandrel support 4 hasa depending shield 12 which covers part of the mandrel head extendingabove the liquid metal L to protect it from oxidation. The annular topflange 9 of the mandrel is fairly deep and is strengthened where itjoins the rest of the mandrel by the fillet 13 which bears on acorrespondingly curved part of the annular recess 5.

The cover plate 15 for securing the mandrel in place has a centeropening and three radial legs 16 which are secured to legs 6 by bolts17. The mandrel support 4 and cover plate 15 are proportioned to providean almost annular space 18 surrounding the mandrel head, as shown inFIG. 1. As also shown in the particular construction of FIG. 1, almostannular space 18 is subdivided clock-wise into three segments 18a, 18band 180, extending partially under cover plate 15, the three segmentsbeing limited at their ends by spaced radial legs 16; thus providingpassageways from space 12 above the molten metal level L to the openatmosphere for the ready escape of gases, if any should collect in thespace 12. This open space 18 (or space segments 18a, 13b and permits theoperator to view the level of metal L from different positions.

The cover plate 15 has a central opening 19 through which the siphontube 20 enters the mandrel. The mandrel has a cylindrical recess or cup21 in the head for receiving molten metal which flows in through thesiphon tube 20. Three radial ducts D connect the cup 21 with the annularspace 22 between the mandrel and the mold liner 2 for the flow of moltenmetal into the space.

The siphon tube 20 delivers molten metal from a supply vessel (notshown) into the hollow cup 21, and the molten metal L flows throughducts D into annular space 22, where it is cooled to form hollow solidbillets. The rate of withdrawal of the resulting continuous hollow solidbillet S is such as to maintain a level of liquid metal L appreciablyabove the bottom of cup 21 so as to submerge the lower end of the siphontube in the liquid metal. The rate of pouring the metal into the cup iscarefully controlled to maintain this level. The maintenance of thismetal in the cup assures a smooth, non-turbulent flow of metal into thespace between the mold 2 and the mandrel M.

The nearly annular space 18 around the mandrel support enables theoperator to see the surface of metal L and adjust the flow to maintainthis level in the cup 21 which is practically level with the metal inthe mold 2. The skirt 12 approaches closely the level of the liquidmetal and practically eliminates the exposed area of the mandrel head 10to oxidizing gases which would react with the graphite at thetemperatures used. To further minimize oxidation of the narrow area ofexposed mandrel small beads of graphite may be floated on the metalaround the mandrel to cover this space between the skirt and the metal.

The mandrel head is the subject of the copending patent application ofWilliam H. Ludwig, having a common assignee with the instantapplication, Ser. No. 398,- 844, filed Sept. 24, 1964.

The mandrel may have a hollow central lower portio in which either orboth gas lubricant supply means and internal cooling means are employedwhich is the subject of the copending patent application of William A.Wood and Camille A. Zeldin, having a common assignee with the instantapplication, Ser. No. 396,687, filed Sept. 15, 1964.

I claim:

1. In apparatus for the continuous casting of hollow metal billets whichincludes an upright stationary outer annular graphite mold with an openended bottom mounted snugly within an annular mold support, an innerannular upright hollow graphite mandrel extending into the annular moldfrom above to provide an interior annular space between the mandrel andthe mold, the annular mandrel forming an upright hollow inner chamberopen at its top and closed at its bottom for receiving and flowingtherefrom a body of molten metal, a plurality of peripherally spacedducts extending through the wall or the lower portion of the mandrelchamber and cornrnunicating with the upper portion of the annular spacebetween the annular mandrel and the annular mold, and a feed pipeextending into the mandrel chamber, so that molten metal may flowcontinuously through the feed pipe downwardly into the mandrel chamberand thence through the ducts into the annular space between the annularmandrel and the annular mold where molten metal freezes to form acontinuous progressively advancing hollow billet, the improvement incombination therewith which comprises:

(a) the inner annular upright hollow mandrel (M) is in the form of aremovable peripheral sleeve having a mandrel head fitting snugly in andsupported exteriorly by an outer annular mandrel head support (4).

(b) the outer mandrel head support (4) is securable to and detachablyremovable from the annular mold support (1);

(c) the outer annular mandrel head support (4) is provided with anannular depending shield portion (12) into which the annular mandrel (M)fits snugly to protect a part of the annular mandrel (M) above theoperating level (L) of casting molten metal (L) in the mandrel chamber(21) and the annular space (22) between the annular mold (2) and theannular mandrel (M); and

(d) the inner annular mandrel (M) and the outer annular mold (2) areuniformly spaced from each other to provide an annular space (22) ofpredetermined cross-section to produce a continuous hollow billet (S)having a solid wall of uniform predetermined thickness.

2. Apparatus according to claim 1, in which a removable cover andholding plate with a central opening (19 for the feed pipe (26') restson the top of the inner annular mandrel (M) for holding it in place; andthe plate (15) extends over and is securable to the top of the outerannular mandrel head support (4).

3. Apparatus according to claim 1, in which a removable cover andholding plate (15) with a central opening (19) for the feed pipe (211)rests on the top of the inner annular mandrel (M) for holding it inplace; and the plate is provided with a plurality of spaced radial legs(16) extending over and securable to the top of the outer annularmandrel head support (4).

4. Apparatus according to claim 1, in which a removable cover andholding plate (15) with a central opening (19) for the feed pipe (29)rests on the top of the inner annular mandrel (M) for holding it'i'nplace; the plate (15) is provided with a plurality of radial legs (16)extending over and securable to the top of the outer annular mandrelhead support (4) and the annular mandrel head support (4) is providedwith at least one annular depending flange (7) to center the annularmandrel head support (4) on the annular mold support (1).

5. Apparatus according to claim 1, in which the inner annular dependentshield portion (12) of the annular mandrel head (11)) extends downwardlyan appropriate distance to provide an upper open space (12') above thenormal molten metal level (L) in'the annular space (22) between theannular mandrel (M) and the annular mold (1) in which the level (L) ofthe molten metal level may freely rise and fall.

6. Apparatus according to claim 1, in which a removable cover andholding plate (15) provided witha central opening (19) for the feed pipe(2%) rests on the top of the inner annular mandrel (M) for holding it inplace; the plate (15) extends over and is securable to the top of theouter annular mandrel head support (4); and

the removable cover and holding plate (15) is shaped to provide analmost annular open space (18) extending outwardly from but surroundingthe annular mandrel (M) and extending under the mandrel head support (4)to the open space (12) below to provide an opening through which anoperator can view from different positions the level of molten metal (L)in the annular space (22) between the annular mandrel (M) and theannular mold (1) and through which gases may escape to the openatmosphere.

7. Apparatus according to claim 1, in which the top portion of theannular mandrel (M) is in the form of an outwardly extending annularflange (9') provided with an annular under-recess portion (5); the outermandrel head support (4) is provided with an annular fillet portion(13); and the recess portion (5) of the flange (9) and the filletportion (13) of the mandrel head support (4) fit snugly into and againstone another.

8. Apparatus according to claim 6, in which the almost annular space(18) is subdivided into a plurality of seg ments (18a), (18b), (18c),extending partially under cover plate (15) to' the annular space (12) inthe mandrel head support for and the annular space (22) above the moltenmetal level (L), the segments being limited at their ends by the spacedradial legs (16).

References Cited UNITED STATES PATENTS WILLIAM I. STEPHENSON, PrimaryExaminer.

J. SPENCER OVERHOLSER, Examiner.

' R. s. ANNEAR, Assistant Examiner.

1. IN APPARATUS FOR THE CONTINUOUS CASTING OF HOLLOW METAL BILLETS WHICHINCLUDES AN UPRIGHT STATIONARY OUTER ANNULAR GRAPHITE MOLD WITH AN OPENENDED BOTTOM MOUNTED SNUGLY WITHIN AN ANNULAR MOLD SUPPORT, AN INNERANNULAR UPRIGHT HOLLOW GRAPHITE MANDREL EXTENDING INTO THE ANNULAR MOLDFROM ABOVE TO PROVIDE AN INTERIOR ANNULAR SPACED BETWEEN THE MANDREL ANDTHE MOLD, THE ANNULAR MANDREL FORMING AN UPRIGHT HOLLOW INNER CHAMBEROPEN AT ITS TOP AND CLOSED AT ITS BOTTOM FOR RECEIVING AND FLOWINGTHEREFROM A BODY OF MOLTEN METAL, A PLURALITY OF PERIPHERALLY SPACEDDUCTS EXTENDING THROUGH THE WALL OF THE LOWER PORTION OF THE MANDRELCHAMBER AND COMMUNICATING WITH THE UPPER PORTION OF THE ANNULAR SPACEBETWEEN THE ANNULAR MANDREL AND THE ANNULAR MOLD, AND A FEED PIPEEXTENDING INTO THE MANDREL CHAMBER, SO THAT MOLTEN METAL MAY FLOWCONTINUOUSLY THROUGH THE FEED PIPE DOWNWARDLY INTO THE MANDREL CHAMBERAND THENCE THROUGH THE DUCTS INTO THE ANNULAR SPACE BETWEEN THE ANNULARMANDREL AND THE ANNULAR MOLD WHERE MOLTEN METAL FREEZES TO FORM ACONTINUOUS PROGRESSIVELY ADVANCING HOLLOW BILLET, THE IMPROVEMENT INCOMBINATION THEREWITH WHICH COMPRISES: (A) THE INNER ANNULAR UPRIGTHHOLLOW MANDREL (M) IS IN THE FORM OF A REMOVABLE PERIPHERAL SLEEVEHAVING A MANDREL HEAD (10) FITTING SNUGLY IN AND SUPPORTED EXTERIORLY BYAN OUTER ANNULAR MANDREL HEAD SUPPORT (4). (B) THE OUTER MANDREL HEADSUPPORT (4) IS SECURABLE TO AND DETACHABLY REMOVABLE FROM THE ANNULARMOLD SUPPORT (1) (C) THE OUTER ANNULAR MANDREL HEAD SUPPORT (4) ISPROVIDED WITH AN ANNULAR DEPENDING SHIELD PORTION (12) INTO WHICH THEANNULAR MANDREL (M) FITS SNUGLY TO PROTECT A PART OF THE ANNULAR MANDREL(M) ABOVE THE OPERATING LEVEL (L) OF CASTING MOLTEN METAL (L'') IN THEMANDREL CHAMBER (21) AND THE ANNULAR SPACE (22) BETWEEN THE ANNULAR MOLD(2) AND THE ANNULAR MANDREL (M); AND (D) THE INNER ANNULAR MANDREL (M)AND THE OUTER ANNULAR MOLD (2) ARE UNIFORMLY SPACED FROM EACH OTHER TOPROVIDE AN ANNULAR SPACE (22) OF PREDETERMINED CROSS-SECTION TO PRODUCEA CONTINUOUS HOLLOW BILLET (S) HAVING A SOLID WALL OF UNIFORMPREDETERMINED THICKNESS.